Amphiblestrum auritum (Hincks, 1877)

Colonies are multiserial, encrusting, forming extensive sheets. Early astogeny has apparently not been described.

Autozooids are elongated, rounded rhomboidal in outline shape, small, about 0.4 mm long by 0.3 mm wide in material from the Red Crag. A shelf-like cryptocystal frontal wall occupies a third or less of the frontal surface and is depressed and granular. The proximal gymnocyst is narrow and often obscured by avicularia. The opesia is extensive, pear-shaped, with or without a pair of slight lateral indentations located mid-length or in the distal third; the proximal edge is concave. Four oral spine bases may be visible in younger zooids but are either lacking in older zooids or reduced to a single spine base on one of the opesial indentations. Ovicells are abundant, globular, peaked, the ectooecium containing a rounded triangular proximal window, flared outwardly at the proximolateral corners, that exposes the entooecium.

Avicularia are abundant and interzooidal, overgrowing the proximal gymnocyst of the autozooids. Non-ovicellate autozooids are usually followed by a single avicularium, variably oriented but often directed proximally, whereas ovicellate autozooids are followed by a pair of avicularia directed distolaterally or laterally. The avicularian rostrum is triangular and pointed, raised distally.